FT24C512A

DEVICE ADDRESSING

The 2-wire serial bus protocol mandates an 8 bits device address word after a START bit condition to

invoke a valid read or write command. The first four most significant bits of the device address must be

1010, which is common to all serial EEPROM devices. The next three bits are device address bits. These

three device address bits (5

match is made, the EEPROM device outputs an ACKNOWLEDGE signal after the 8

otherwise the chip will go into STANDBY mode. However, matching may not be needed for some or all

device address bits (5

8

mode.

WRITE OPERATION

(A)

BYTE WRITE

A write operation requires two 8-bit data word address following the device address word and

ACKNOWLEDGE signal. Upon receipt of this address, the EEPROM will respond with a “0” and then

clock in the first 8-bit data word. Following receipt of the 8-bit data word, the EEPROM will again

output a “0”. The addressing device, such as a microcontroller, must terminate the write sequence

with a STOP condition. At this time the EEPROM enters into an internally-timed write cycle state. All

inputs are disabled during this write cycle and the EEPROM will not respond until the writing is

completed (figure 5).

(B)

PAGE WRITE

The 512K EEPROM are capable of 128-byte page write.

A page write is initiated the same way as a byte write, but the microcontroller does not send a STOP

condition after the first data word is clocked in. The microcontroller can transmit up to 127 more data

words after the EEPROM acknowledges receipt of the first data word. The EEPROM will respond

with a “0” after each data word is received. The microcontroller must terminate the page write

sequence with a STOP condition (see Figure 6).

The lower 7 bits of the data word address are internally incremented following the receipt of each data

word. The higher data word address bits are not incremented, retaining the memory page row

location. If more than 128 data words are transmitted to the EEPROM, the data word address will

“roll over” and the previous data will be overwritten.

(C)

ACKNOWLEDGE POLLING

ACKNOWLEDGE polling may be used to poll the programming status during a self-timed internal

programming. By issuing a valid read or write address command, the EEPROM will not acknowledge

at the 9

programming completes and the chip has returned to the STANDBY mode, the device will return a

valid ACKNOWLEDGE signal at the 9

© 2009 Fremont Micro Devices Inc.

DS3009E-page

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